JPH085046A - Mixing method for combustion gas - Google Patents

Abstract

PURPOSE:To suppress unburned gas such as carbon monoxide and aromatic hydrocarbon in exhaust gas and harmful substance such as organic chlorine compound containing dioxin to low concentration in an incinerating furnace for waste such as municipal refuse, etc. CONSTITUTION:Combustion gas 9 containing much unburned gas of the upstream side of the moving direction of materials 7 to be incinerated and combustion gas 10 of the downstream side of the moving direction to be branched via a barrier 6 provided near the outlet 1a of a combustion chamber 1 are combined on the back surface of the barrier 6 between the barrier 6 and the wall of a combustion chamber furnace to allow both the combustion gases 9 and 10 to be collided to be mixed. A ratio of the downstream side combustion gas flow rate F1 at the channel of the gas 10 between the barrier 6 and the furnace wall to the upstream side combustion gas flow rate F2 at the channel of the gas 9 between the barrier 6 and the furnace wall is set to a range of F1:F2=(8:2)-(5.5:4.5).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to incinerating municipal waste, sewage sludge, night soil sludge, combustible industrial waste, etc. in an incinerator such as a stoker furnace (also referred to as a combustion furnace).
Using a barrier, the combustion gas containing a large amount of unburned gas on the upstream side in the dust flow direction and the downstream combustion gas containing a large amount of oxygen are made to collide with each other to mix and stir, and carbon monoxide and aromatics in the exhaust gas The present invention relates to a method for mixing unburned gas containing a large amount of hydrocarbons, etc. and combustion gas for reducing harmful substances such as organic chlorine compounds containing dioxins.

[0002]

2. Description of the Related Art Conventionally, an incinerator such as a stoker furnace
When incinerating municipal waste, sewage sludge, human waste sludge and combustible industrial waste (collectively, "waste such as municipal waste"), carbon monoxide and aromatic hydrocarbons in exhaust gas The reduction of harmful substances such as unburned gas containing a large amount of gas and organic chlorine compounds containing dioxins (hereinafter referred to as "unburned gas and harmful substances") has been an issue.

As a technique for solving the above problems, we have
The following proposals have been made in Japanese Patent Application Laid-Open No. 2-166306, "Title of Invention: Method for Suppressing Dioxins in Waste Incinerators". In a method for mixing combustion gas in a stoker furnace called a double-flow furnace, a barrier for branching the combustion gas is provided, and a combustion gas containing a large amount of unburned gas and a combustion gas containing a large amount of oxygen are provided. A method of suppressing unburned gas, harmful substances and the like by mixing in a predetermined residence space and maintaining a high temperature for a predetermined time (hereinafter referred to as "prior art 1").

In Japanese Utility Model Application Laid-Open No. 4-108130, "Title of Invention: Combustion Gas Mixing Structure in Waste Incinerator", a combustion chamber 1 in a stoker furnace as shown in FIG.
There is disclosed a structure in which the mixing of the combustion gas is promoted by a barrier 6 for dividing the combustion gas at the outlet 1a (hereinafter referred to as "prior art 2").

Japanese Unexamined Patent Publication No. 5-126326, "Title of Invention: Incinerator" discloses a method for mixing combustion gas in a fluidized bed furnace and a stoker furnace by a barrier (hereinafter referred to as "prior art 3"). ).

[0006] In all of the prior arts 1 to 3, the combustion gas is divided by a barrier or the like in the incinerator, and then merged again to collide with each other to mix and stir to suppress unburned gas and harmful substances. Is the way.

[0007]

However, as in the prior arts 1 to 3, the unburned gas and the harmful substances existing in the exhaust gas are simply mixed and stirred by dividing and joining the combustion gas by the barrier. However, there is a problem that it is difficult to keep the concentration low. That is, in consideration of the flow rate of the combustion gas, the temperature of the combustion gas, and the like, it is important to consider the conditions under which the combustion gases should collide with each other and be mixed and stirred when they merge in the retention space.

The prior arts 1 and 2 do not show the above-mentioned specific contents regarding an effective mixing method for suppressing unburned gas, harmful substances and the like to a low concentration.

In the prior art 3, the numerical value relating to the combustion gas flow velocity of the narrowed portion formed by the furnace wall (combustion gas flow passage between the barrier and the furnace wall) is shown. Since it is affected by the furnace width and the combustion gas temperature, it is not uniquely determined from the flow rate of the combustion gas, and even if the numerical value of the flow rate of the combustion gas is limited, it is effective to suppress unburned gas and harmful substances to low concentrations. It doesn't show the way.

Therefore, an object of the present invention is to incinerate municipal waste, sewage sludge, human waste sludge, combustible industrial waste, etc. in an incinerator such as a stoker furnace by combining the combustion gases divided by a barrier. Provided is a method for mixing combustion gas capable of suppressing unburned gases such as carbon monoxide and aromatic hydrocarbons and harmful substances such as organic chlorine compounds containing dioxins to a low concentration when they are collided and mixed and stirred. Especially.

[0011]

According to the present invention, in an incinerator having a combustion chamber provided with a grate for burning while moving an incineration object, the incineration object is moved near an outlet of the combustion chamber. A barrier for branching the combustion gas on the upstream side in the direction of movement and the combustion gas on the downstream side in the moving direction, and an upstream side combustion gas containing unburned gas generated in large quantities from the incineration object on the upstream side in the moving direction; The downstream side combustion gas containing more oxygen than the upstream side combustion gas is caused to flow into a predetermined retention space mainly from each of the upstream side and the downstream side through the barrier and the combustion chamber furnace wall, and in the retention space, In a method for mixing a combustion gas in which an upstream combustion gas and the downstream combustion gas are collided and mixed with each other, the downstream in a flow path of the downstream combustion gas between the barrier wall and the combustion chamber furnace wall A combustion gas flow rate F1, the ratio between the upstream combustion gas flow rate F2 in the flow path of the upstream combustion gas between the barrier and the combustion chamber furnace wall, F1: F2 =
It is characterized in that it is within the range of 8: 2 to 5.5: 4.5.

The ratio of the sectional area A1 of the narrowest part of the space forming the flow path of the downstream side combustion gas to the sectional area A2 of the narrowest part of the space forming the flow path of the upstream side combustion gas. A
The feature is that the ratio is within the range of 1: A2 = 8: 2 to 5.5: 4.5.

Further, the shortest distance L1 of the narrowest part of the space forming the flow path of the combustion gas on the downstream side and the shortest distance L2 of the narrowest part of the space forming the flow path of the combustion gas on the upstream side.
Are characterized in that each is 0.3 m or more.

Further, the temperature when the combustion gas on the downstream side passes through the flow passage and the temperature when the combustion gas on the upstream side passes through the flow passage are each 830 ° C. or higher. I have.

[0015]

[Function] Dioxins, etc. have the property of being thermally decomposed when the exhaust gas containing them is heated to a high temperature due to their chemical structure. C, which is a heat source for incineration from incineration
A state in which a large amount of unburned gas containing a large amount of O, HC, etc. is generated, and this unburned gas is made to collide with, mixed with, and agitated with a combustion gas containing a large amount of oxygen in a predetermined retention space, and the unburned gas is in a state close to complete combustion. By re-combusting at 2, and maintaining it at a high temperature, it is possible to efficiently thermally decompose dioxin and the like in the exhaust gas generated from the material to be incinerated, and to significantly reduce the generation amount.

After the combustion gas on the upstream side in the flow direction containing a large amount of unburned gas and the combustion gas on the downstream side in the flow direction containing a large amount of oxygen are separated by a barrier, both combustion gases are rejoined in a predetermined retention space. When colliding and burning, (1) combustion gas flow rate ratio, (2) sectional area ratio of the narrowest part of the space forming the combustion gas flow path, and (3) the narrowest part by the method of the present invention described above. By defining the shortest distance of (4) and the temperature (4) when the combustion gas passes through the flow path, it is possible to ensure the action of reducing dioxin and the like.

In the incinerator for waste such as municipal waste (double-flow furnace), the oxygen concentration of the combustion gas containing a large amount of oxygen is 9v on a dry basis due to the influence of the properties of the incineration object.
ol. % To 19 vol. It varies within the range of%. Further, in the combustion gas containing a large amount of unburned gas, the oxygen concentration is 0 vol. %, The carbon monoxide concentration is 0.1 vol. % To 8 vol. It fluctuates to%. Therefore, in the present invention, the combustion gas rich in oxygen has an oxygen concentration of 9 to 19 vo on a dry basis.
l. % Of combustion gas is defined, and combustion gas containing a large amount of unburned gas has a carbon monoxide concentration of 0.1 to 8 vol. It is defined as the combustion gas contained in%.

(1) The combustion gas flow rate ratio is expressed as "F1: F2 =
8: 2 to 5.5: 4.5 ”range of action: When waste such as municipal waste is burned in an incinerator such as a stoker furnace, it contains a large amount of oxygen shunted by the barrier. The downstream combustion gas and the upstream combustion gas containing a large amount of unburned gas are mixed again in a predetermined retention space to collide with each other to mix and stir the incinerator such as the stoker furnace ( Hereinafter, in the "incinerator"), the combustion product gas (combustion gas) generated by the combustion of the incineration object (waste such as municipal waste) in the combustion chamber is the difference in the original size and composition of the incineration object. Therefore, at each point in the incinerator flow direction from the upstream side to the downstream side where the incinerator moves, different gas compositions (main components are oxygen, carbon monoxide,
Carbon dioxide, water vapor and nitrogen), and different gas properties (gas viscosity, dust concentration and viscosity, etc.), and with a certain size of concentration mass. Therefore, the downstream combustion gas containing a large amount of oxygen (flow rate F1)
And the upstream combustion gas containing a large amount of unburned gas (flow rate F
2) After dividing the flow into (1) and (2), the flow rate ratio (expressed as F1: F2) is merged again and collided to mix and stir to suppress the unburned gas and harmful substances present in the combustion gas to a low concentration. Not enough effect.

In order to sufficiently obtain the above effect, oxygen is not generated in the flow path of the combustion gas flowing into the predetermined retention space, that is, the flow path of the combustion gas between the barrier wall and the furnace wall facing the barrier wall. The flow rate ratio between the downstream-side combustion gas flow rate F1 that is largely contained and the upstream-side combustion gas flow rate F2 that is largely contained in unburned gas is "F1: F2 = 8: 2 to 5.5: 4.5". Should be within range. Note that the flow rate ratio does not include fluctuation in a minute time in seconds, and represents an average flow rate ratio.

When the flow rate ratio F1 is made smaller than "F1: F2 = 5.5: 4.5", that is, the combustion gas flow rate F1 on the downstream side containing a large amount of oxygen becomes "F1 <(5.5 / 4. 5)
・ In F2 ″, sufficient oxygen cannot be given to the downstream combustion gas to reduce unburned gas and harmful substances in the upstream combustion gas by mixing, and the effect of reducing unburned gas and harmful substances is reduced. The sufficient amount of oxygen corresponding to the downstream combustion gas flow rate: F1 = 5.5 shown here is larger than the amount of oxygen obtained from the chemical reaction formula required for complete combustion of unburned gas and harmful substances. The amount is the amount necessary for completely burning the unburned gas, harmful substances, etc. by generating a state in which the combustion gas concentration lump is broken into minute concentration lumps to promote the combustion reaction.

On the other hand, when the flow rate ratio F1 is larger than "F1: F2 = 8: 2", that is, when the downstream combustion gas flow rate F1 containing a large amount of oxygen is "F1> (8/2) .F2". , The combustion gas flow is greatly disturbed due to the difference in the flow rate of the combustion gas between the upstream side and the downstream side and the difference in the gas properties, and the upstream side combustion gas flowing in the upstream combustion gas flow path between the barrier and the road wall However, it passes through the vicinity of the barrier or the vicinity of the furnace wall, the effect of promoting the mixing and stirring of the barrier is lowered, and the effect of reducing unburned gas and harmful substances cannot be sufficiently obtained.

(2) The cross-sectional area ratio of the narrowest part of the space forming the combustion gas passage is expressed as "A1: A2 = 8: 2 to 5.5: 4.
Action by in the range of 5 ":. Furnace pressure incinerators are generally -5~-30mmH ₂ O approximately in the negative pressure of this order, that much oxygen between the barrier and the combustion chamber furnace wall The cross-sectional area A1 of the narrowest part of the space part forming the downstream combustion gas flow furnace included and the cross-sectional area of the narrowest part of the space part forming the upstream combustion gas flow furnace containing a large amount of unburned gas A
The cross-sectional area ratio with 2 is "A1: A2 = 8: 2-5.5:
By setting it within the range of 4.5 ", the above combustion gas flow rate ratio can be set within the range of" F1: F2 = 8: 2-5.5: 4.5 ".

(3) Action by setting the shortest distances L1 and L2 of the narrowest part of the space forming the combustion gas flow path to 0.3 m or more: The combustion gas flow rate is affected by the property of the incineration object, It changes moment by moment, and minute drifts occur in the flow of combustion gas on the upstream side and the downstream side. Due to the influence of this uneven flow, dust may start to adhere and accumulate on the barrier wall and the furnace wall facing the barrier wall regardless of the flow velocity of the combustion gas flowing on the upstream side and the downstream side, and the combustion gas flow path may be blocked. The shortest distance L1 at the narrowest part of the space forming the flow path of the combustion gas containing a large amount of oxygen on the downstream side and the shortest distance L2 at the narrowest part of the space forming the combustion gas flow path containing a large amount of the unburned gas on the upstream side. Is 0.3 m or more, the blockage of the combustion gas flow path caused by dust can be prevented.

(4) Operation by setting the temperature of the combustion gas passing through the flow path to 830 ° C. or higher: In the present invention, the combustion gas on the downstream side containing a large amount of oxygen and the unburned gas are contained. Carbon monoxide at the outlet of the incinerator by adding the condition that the temperature of the combustion gas is 830 ° C. or higher to the method of mixing and stirring the upstream combustion gas with the above flow rate ratio. Concentration is a few ppm (10p
(less than pm).

Unburned components such as carbon monoxide and hydrocarbons generated from wastes such as municipal waste decompose at higher temperatures, but the temperature deviation at which the decomposition rate of the unburned components changes around 830 ° C. It has a turning point. The inflection point temperature of 830 ° C. is a temperature that is unique to incineration of waste such as municipal waste, which is affected by combustion gas properties, that is, dust containing heavy metals in the combustion gas, hydrogen chloride gas, soot, and the like. Is. Therefore, in the present invention, the temperature of the combustion gas is set to 83
It should be limited to 0 ° C or higher.

For example, comparing a gas turbine or an industrial furnace with an incinerator of waste such as municipal waste, the gas turbine or the industrial furnace has a clean combustion in which a fuel such as city gas or propane is burned, Since there is no influence as described above in the incinerator that burns waste such as municipal waste, the inflection point temperature is several tens of degrees lower than that (830 ° C.) of the waste such as municipal waste.

It should be noted that, even in the method of mixing the combustion gas in the incinerator outside the scope of the present invention without using the barrier, or in the method of mixing the combustion gas outside the flow rate ratio of the present invention even if the barrier is used, the above-mentioned temperature is used. Below the inflection point of 830 ° C., it is difficult to reduce the unburned component to several ppm.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 2 is a cross-sectional view showing a fully continuous inclined grate type double-flow furnace according to an embodiment of the present invention. Reference numeral 1 in FIG. 2 denotes a combustion chamber of a fully continuous inclined grate type double-flow furnace (hereinafter referred to as “double-flow furnace”), and one side (left side of FIG. 2) of this combustion chamber 1 is incinerated. A hopper 2 is provided for throwing a product (waste such as municipal waste) 7 into the combustion chamber 1. At the bottom of the combustion chamber 1, a mesh-shaped grate 11 that burns while moving the incineration object 7 is provided so as to incline toward the direction away from the hopper 2, and the grate 11 has two A step is formed. A cavity block 5 to which a supply pipe 4 for supplying combustion air is connected is provided below the grate 11. A combustion chamber outlet 1a is provided above the combustion chamber on the side opposite to the hopper 2, and the outlet 1a is provided with a boiler portion (hereinafter, “boiler portion”) of a gas cooling facility downstream from the outlet 1a.
3) is connected and provided. A barrier (also referred to as a baffle plate) 6 for dividing the combustion gas is provided in the combustion chamber 1 near the outlet 1a.

The incineration of waste such as municipal waste in the double-flow furnace having such a structure will be described below. First, as shown in FIG.
And the combustion air 8 is supplied to the incinerator 7 moving on the grate 11 through the supply pipes 4 and the cavity block 5, while the incinerator 7 is dried and burned. At this time, the supply pipe 4 on the side close to the hopper 2 (upstream side)
And the amount of combustion air supplied through the cavity block 5 is made smaller than the amount of combustion air supplied through the supply pipe 4 and the cavity block 5 on the other side (downstream side), so that the material to be incinerated on the upstream side is reduced. A large amount of unburned gas is generated from 7. The combustion gas 9 (indicated by an arrow) containing a large amount of unburned gas thus generated rises in the combustion chamber 1 and passes from above the barrier 6 to between the barrier 6 and the furnace wall of the combustion chamber 1. Then, it flows into the back side (top side) of the barrier 6.

On the other hand, a combustion gas 10 (indicated by an arrow) that is completely combusted by the air supplied through the supply pipe 4 and the cavity block 5 on the downstream side of the grate 11 and contains a large amount of oxygen.
Rises in the combustion chamber 1, passes from below the barrier 6 between the barrier 6 and the furnace wall of the combustion chamber 1, and flows into the back side of the barrier 6.

The combustion gas 9 and the combustion gas 10 are
Merging in a predetermined retention space on the back side (upper side) of the barrier 6,
Here, the combustion gases collide with each other, and they are sufficiently mixed and stirred for a predetermined time to achieve complete combustion, the high temperature state is maintained, and harmful substances such as organic chlorine compounds including dioxin are thermally decomposed. Then, the exhaust gas after combustion (combustion gas discharged from the outlet 1a) flows into the boiler portion 3 downstream of the outlet 1a and is cooled.

FIG. 8 is a sectional view showing a grate furnace with a double-flow type waste heat boiler according to another embodiment of the present invention. As in the case of FIG. 2, the incinerator shown in FIG. 8 is also an unburned gas containing a large amount of carbon monoxide and aromatic hydrocarbons in the exhaust gas as well as harmful substances such as organic chlorine compounds containing dioxins, by carrying out the method of the present invention. Can be reduced to a low concentration.

FIG. 9 is a sectional view showing one embodiment of the shape of the barrier of the incinerator, and FIG. 10 is a sectional view taken along the line AA of FIG. The barrier 6 shown in FIGS. 9 and 10 has a large throughput, for example, 1
It is an effective shape when it is 6.7 t / h (400 t / 24 h) or more. In the stoker furnace, since the furnace width becomes wider according to the amount of processing, the support wall 12 is provided so as to divide the auxiliary flue 13 into two as shown in FIG. 10. Further, the barrier 6 and the support wall 12 may have a water cooling structure having a heat exchange section inside. 2, FIG. 8, FIG. 9, and FIG. 10 are only one embodiment of the present invention, and the present invention is not limited to the incinerator described above.

Using the double-flow furnace shown in FIG.
(1) flow rate ratio, (2) cross-sectional area ratio, (3) blocking prevention effect,
And, (4) the temperature effect was investigated.

(1) Flow rate ratio: The barrier 6 and the combustion chamber 1 of the double-flow furnace with a boiler shown in FIG. 2 having an incineration treatment amount (hereinafter referred to as "treatment amount") of about 6 tons / hour (t / h). Downstream combustion gas 10 containing a large amount of oxygen in the flow path between the furnace and the furnace wall
Of the carbon monoxide (CO ) Was investigated. Since the carbon monoxide concentration changes depending on the oxygen concentration, the oxygen concentration of 12 vol. % (The same applies to the carbon monoxide concentration measurement below). The result is shown in FIG. As shown in FIG. 1, the flow rate ratio is “F1: F2 = 8: 2 to 5.5:
When it is within the range of 4.5 ", the concentration of carbon monoxide is several ppm (specifically, 3 p
It can be seen that it can be suppressed to as low as (pm or less).
The hydrocarbon concentration also behaves similarly to the carbon monoxide concentration.

The concentration (I) of dioxins corresponding to these carbon monoxide concentrations (oxygen concentration 12 vol.%)
-TEQ ng / Nm ³ ) was examined in the boiler section 3. The result is shown in FIG. As shown in FIG. 3, the dioxin concentration is determined by the flow rate ratio “F1: F2 = 8: 2 to 5.5:
It can be seen that it shows a low value almost similar to the behavior of the carbon monoxide concentration and the total hydrocarbon concentration corresponding to 4.5 ".

(2) Cross-sectional area ratio: In the double-flow furnace shown in FIG. 2, the cross-sectional area A1 and the unburned gas in the narrowest part of the space forming the flow path of the combustion gas 10 on the downstream side containing a large amount of oxygen are The carbon monoxide concentration in the exhaust gas of the boiler part 3 was investigated with respect to the flow rate ratio of the cross-sectional area A2 of the space of the narrowest part forming the flow path of the combustion gas 9 on the upstream side, which is contained a lot. FIG. 4 shows the results. As shown in FIG. 4, the cross-sectional area ratio is “A1: A2 =
8: 2 to 5.5: 4.5 ", it can be seen that the carbon monoxide concentration can be suppressed to be lower than that of the cross-sectional area ratio outside the range. It behaves similarly to carbon concentration, and the cross-sectional area ratio is "A1: A
In the case of 2 = 8: 2 to 5.5: 4.5 ", it can be suppressed to be lower than in the case of the cross-sectional area ratio outside the range.

Next, in the double-flow furnace (shown in FIG. 2) having a throughput of about 3 to 8 t / h, the flow rate F1 of the downstream combustion gas 10 containing a large amount of oxygen and a large amount of unburned gas are contained. Flow rate ratio “F1: F2” to the flow rate F2 of the combustion gas 9 on the upstream side
Combustion by changing the flow rate, and the flow rate F of the combustion gas 10 on the downstream side is changed.
1, the cross-sectional area A1 of the narrowest part of the space forming the downstream combustion gas flow furnace, and the space forming the upstream combustion gas flow furnace with respect to the flow rate ratio of the flow rate F2 of the upstream combustion gas 9. The cross-sectional area ratio with the cross-sectional area A2 of the narrowest part was examined. The result is shown in FIG. As shown in FIG. 5, the cross-sectional area ratio “A1: A2 =
8: 2 to 5.5: 4.5 ”is the flow rate ratio“ F1: F2 =
It can be seen that the ratio is almost the same as the ratio of 8: 2 to 5.5: 4.5 ". The position of the barrier 6 installed in the furnace of each factory having different throughput depends on the quality of the incinerated material. However, the above result does not change regardless of the arrangement of the barrier 6.

(3) Blocking prevention effect: In the double-flow furnace shown in FIG. 2, the narrowest space of the space forming the flow path of the upstream combustion gas 9 containing a large amount of unburned gas divided by the barrier 6 The shortest distance L2 is set to 0.25 m, which is out of the range of the present invention, and the flow velocity of the combustion gas 9 is 1 m / s, 6 m / s or 15 m / s.
Then, the flow rate F2 of the combustion gas 9 was changed at each flow velocity, and the clogging of the narrowest portion was examined. The flow rate F2 was changed by changing the throughput of the incineration material. As a result, the flow rate of the combustion gas fluctuates from moment to moment, and due to the effect of minute uneven flow, the dust floating in the combustion gas adheres to the barrier 6 and the furnace wall of the combustion chamber 1 facing the barrier 6 regardless of the flow velocity. Then, the deposition started to occur, and eventually the flow path was blocked.

Next, in the double-flow furnace shown in FIG. 2, the shortest distance L of the narrowest part of the space forming the flow path of the upstream combustion gas 9 containing a large amount of unburned gas divided by the barrier 6.
I investigated how much 2 is needed. That is, the shortest distance L
2 was changed from 0.17 m to 0.51 m, and the clogging of the narrowest part was examined. The shortest distance L2 of the narrowest part was changed by stacking bricks in the flow path. The tests are general municipal waste, plastic waste,
Separation waste containing plastics and incombustibles, mixing of general municipal waste and sewage sludge, mixing of general municipal waste and human waste sludge, and any one of the above-mentioned sewage sludge were used as incinerators. Combustion gas flow velocity varies from 2m / s to 17m / s depending on the nature of the incinerated material.
Varied between. As a result, when the shortest distance L2 of the narrowest portion is less than 0.3 m due to a change in the combustion gas flow rate of the incineration object and a change in the property of the incineration object, the flow path is generated regardless of the flow rate of the combustion gas. Dust floating in the combustion gas flowing in the furnace started to adhere and accumulate on the barrier wall 6 and the furnace wall of the combustion chamber 1 facing the barrier wall 6, and eventually blocked the flow path, hindering the operation. On the other hand, when the shortest distance L2 of the narrowest part was 0.3 m or more, no dust adhered and accumulated.

(4) Temperature effect: against changes in the combustion gas temperature at the combustion chamber outlet 1a (hereinafter referred to as "furnace outlet temperature") when waste such as municipal waste is burned by the double-flow furnace shown in FIG. The behavior of the carbon monoxide concentration in the exhaust gas of the boiler part 3 was investigated. The result is shown by the solid line in FIG. For comparison, the behavior of the carbon monoxide concentration in the exhaust gas with respect to the change in the furnace outlet temperature of the propane combustion exhaust gas was also investigated in a general industrial furnace. The result is also shown in FIG. 6 by a broken line.

As can be seen from FIG. 6, when waste such as municipal waste is burned, the temperature inflection point at which the decomposition rate of unburned components changes becomes 830 ° C. or higher, so the furnace outlet temperature is set to the above temperature. It can be seen that the carbon monoxide concentration can be suppressed to about several ppm by setting the inflection point to 830 ° C. or higher. That is, when waste such as municipal waste is burned in a double-flow furnace, dust with complicated components is generated in the combustion gas, including chlorine-based hydrogen chloride gas having a quenching effect and heavy metals. As compared with the case of propane combustion, the combustion gas properties become more complicated, and a temperature difference of several tens of degrees occurs at the temperature inflection point for reducing the concentration of unburned components such as carbon monoxide and hydrocarbons. As shown in the figure, the temperature inflection point for combustion of waste such as municipal waste (●) is higher than the temperature inflection point for propane combustion (▲).

Next, in the double-flow reactor with a boiler having a throughput of about 6 t / h shown in FIG. 2, the flow rate F1 of the downstream combustion gas 10 containing a large amount of oxygen and the upstream flow containing a large amount of unburned gas. The carbon monoxide concentration in the exhaust gas of the boiler part 3 was examined with respect to the change in the flow rate ratio of the combustion gas flow rate 9 on the side to the flow rate F2. At this time, the average temperature of the downstream combustion gas 10 containing a large amount of oxygen was changed from 700 ° C to 900 ° C. On the other hand, the temperature of the upstream combustion gas 9 containing a large amount of unburned gas was set to 900 ° C. or higher. FIG. 7 shows the result. From FIG. 7, the carbon monoxide concentration is several ppm (10 pp
(less than m) is that the downstream combustion gas temperature is 8
It can be seen that the temperature is 30 ° C. or higher.

Further, the flow rate ratio in the double-flow furnace having a throughput of about 5.5 t / h is defined as "F1: F2 =" within the range of the present invention.
7: 3 "and the temperature of the combustion gas 10 on the downstream side is 83
As a result of measuring the carbon monoxide concentration of the boiler part 3 when the temperature of the combustion gas 9 on the upstream side is 850 ° C. at 0 ° C.,
The concentration could be suppressed to several ppm.

[0045]

As described above, according to the present invention, when incinerating municipal waste, sewage sludge, night soil sludge, combustible industrial waste, etc. by an incinerator such as a stoker furnace, the garbage is removed by the barrier. In the method in which the combustion gas containing a large amount of unburned gas on the upstream side and the combustion gas on the downstream side containing a large amount of oxygen are diverted and then merged again to cause mixing and mixing, the combustion gas flow ratio By defining the cross-sectional area ratio of the narrowest part of the space forming the combustion gas flow path, the shortest distance of the narrowest part, and the temperature at which the combustion gas passes through the flow path, monoxide in the exhaust gas Unburned gas containing a large amount of carbon and aromatic hydrocarbons and harmful substances such as organic chlorine compounds containing dioxins can be reduced and kept at a low concentration, thus providing industrially useful effects.

[Brief description of drawings]

FIG. 1 shows a processing amount of about 6 t / h according to an embodiment of the present invention.
In the fully continuous inclined grate type double flow reactor with boiler,
The carbon monoxide concentration in the exhaust gas of the boiler is shown against the flow rate ratio "F1: F2" between the downstream combustion gas flow rate F1 containing a large amount of oxygen and the upstream combustion gas flow rate F2 containing a large amount of unburned gas. It is a graph.

FIG. 2 is a cross-sectional view showing a fully continuous inclined grate type double-flow furnace according to an embodiment of the present invention.

FIG. 3 is a graph showing the concentration of dioxins corresponding to the concentration of carbon monoxide in the exhaust gas according to the example of the present invention.

FIG. 4 is a cross-sectional area A1 of the narrowest part of the space forming the downstream side combustion gas flow path containing a large amount of oxygen in the fully continuous tilted grate double-flow reactor with a boiler according to the embodiment of the present invention.
And the cross-sectional area ratio A2 between the cross-sectional area A2 of the narrowest part of the space forming the upstream combustion gas flow path containing a large amount of unburned gas, "A1:
It is a graph which shows the carbon monoxide concentration in the exhaust gas of a boiler part with respect to A2 ".

FIG. 5 is a processing amount of about 3 to 8 t according to the embodiment of the present invention.
/ H in a fully continuous inclined grate type double-flow reactor with a boiler, the downstream side combustion gas flow rate F1 containing a large amount of oxygen,
The cross-sectional area A of the narrowest part of the space forming the downstream combustion gas flow path containing a large amount of oxygen with respect to the flow rate ratio “F1: F2” with the upstream combustion gas flow rate F2 containing a large amount of unburned gas
The cross-sectional area ratio "A of 1 to the cross-sectional area A2 of the narrowest part of the space forming the upstream combustion gas flow path containing a large amount of unburned gas
1 is a graph showing 1: A2 ″.

FIG. 6 is a graph showing the behavior of the carbon monoxide concentration in the exhaust gas of the boiler section with respect to the furnace outlet temperature for propane combustion and waste combustion such as municipal waste according to the embodiment of the present invention.

FIG. 7 shows a throughput of about 6 t / h according to an embodiment of the present invention.
In the fully continuous inclined grate type double flow reactor with boiler of
The average temperature of the downstream combustion gas containing a large amount of oxygen is 70
When changing from 0 ℃ to 900 ℃,
The carbon monoxide concentration in the exhaust gas of the boiler part is compared with the flow ratio "F1: F2" between the downstream combustion gas flow rate F1 containing a large amount of oxygen and the upstream combustion gas flow rate F2 containing a large amount of unburned gas. It is a graph shown.

FIG. 8 is a sectional view showing a grate furnace with a double-flow waste heat boiler according to another embodiment of the present invention.

FIG. 9 is a cross-sectional view showing one embodiment of the shape of the barrier of the incinerator.

10 is a cross-sectional view taken along the line AA of FIG.

FIG. 11 is a sectional view showing an example of a conventional stoker furnace.

[Explanation of symbols]

 1: Combustion chamber 1a: Combustion chamber outlet 2: Hopper 3: Boiler part 4: Supply pipe 5: Cavity block 6: Barrier 7: Incinerator 8: Combustion air 9: Combustion gas containing a lot of unburned gas 10: Combustion gas containing a large amount of oxygen 11: Grate 12: Support wall 13: Secondary flue

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Nagaseki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Eiichi Shibuya 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Tube Co., Ltd.

Claims (4)

[Claims] 1. An incinerator having a combustion chamber equipped with a grate for burning while moving an incineration object, in the vicinity of an outlet of the combustion chamber, a combustion gas on the upstream side in the moving direction of the incineration object, and the A barrier for branching off the combustion gas on the downstream side in the moving direction is provided, and the upstream combustion gas containing unburned gas generated in large quantities from the incineration material on the upstream side in the moving direction and oxygen above the upstream combustion gas. The downstream side combustion gas containing a large amount of is mainly introduced from each of the upstream side and the downstream side into the predetermined retention space through the space between the barrier and the combustion chamber furnace wall, and the upstream side combustion gas and the downstream side in the retention space. A method for mixing combustion gas in which combustion gas is collided and mixed, wherein the downstream side combustion gas flow rate F1 in the flow path of the downstream side combustion gas between the barrier wall and the combustion chamber furnace wall, The ratio of the upstream combustion gas flow rate F2 in the flow path of the upstream combustion gas between the wall and the combustion chamber furnace wall, F1:
F2 = 8: 2 to 5.5: 4.5 The method of mixing combustion gas, characterized in that it is within the range. 2. The ratio of the sectional area A1 of the narrowest part of the space forming the flow path of the downstream combustion gas to the sectional area A2 of the narrowest part of the space forming the flow path of the upstream combustion gas. To A1:
A2 = 8: 2 to 5.5: 4.5.
A method for mixing combustion gases as described. 3. The shortest distance L1 of the narrowest part of the space forming the flow path of the combustion gas on the downstream side and the shortest distance L2 of the narrowest part of the space forming the flow path of the combustion gas on the upstream side, The combustion gas mixing method according to claim 1 or 2, wherein each has a length of 0.3 m or more. 4. The temperature when the combustion gas on the downstream side passes through the flow passage and the temperature when the combustion gas on the upstream side passes through the flow passage are each 830 ° C. or higher. 2. The method for mixing combustion gases according to 2 or 3.